Visible Light‐Switchable Lattice Oxygen Sites for Selective C−H and C(O)−C Bond Electrooxidation

Lattice‐oxygen is highly oxidizable, ideal for electrocatalytic C−H oxidation but insufficient alone for C(O)−C bond cleavage due to the non‐removable nature of lattice sites. Here, we present a visible light‐assisted electrochemical method of in‐situ formulating removable lattice‐oxygen sites in a nickel‐oxyhydroxide (ESE‐NiOOH) electrocatalyst. This catalyst efficiently converts aromatic alcohols and carbonyls with C(O)−C fragments from lignin and plastics into benzoic acids (BAs) with high yields (83–99%). Without light irradiation, ESE‐NiOOH’s intrinsic lattice‐oxygen is non‐removable and inert for C(O)−C bond cleavage. In‐situ characterizations show light‐induced lattice‐oxygen removal and regeneration via OH– refilling. Theoretical calculations identify the nucleophilic oxygen attack on ketone‐derived carbanion as a rate‐determining step, which can be remarkably facilitated by removable lattice‐oxygen to activate α‐C−H bonds. As a proof‐of‐concept, an “electrochemical funnel” strategy is developed for high‐efficiency upgrading aromatic mixtures with C(O)−C moieties into BA with up to 94% yield. This in‐situ removal‐regeneration approach for lattice sites opens an avenue for the tailored design of interfacial electrocatalysts to selectively upcycle waste carbon sources into valuable products.